The present invention relates to a check valve arrangement allowing unidirectional flow of a pressure medium while preventing fluid flow in the opposite direction.
Commonly used check valves include a channel opening into a valve chamber with a valve seat machined around the opening. A closure member, e.g. a steel ball, interacts with the valve seat to open or close the valve. Sometimes, the closure member is spring-biased toward the valve seat. When the pressure in the channel exceeds the pressure in the valve chamber and, if applicable, exerts an opening force greater than the spring force, the closure member is lifted off the valve seat, and fluid can flow from the channel through the opening into the valve chamber. However, if the pressure conditions change, the closure member shuts off the channel opening and prevents a flow of fluid in the opposite direction.
A check valve as it is currently used in a hydraulic anti-lock brake system includes steel balls that serve as valve closure elements and interact with valve seats machined into fluid channels. To this end, each channel has a widened port accommodating the steel ball. Where the channel gets narrower, the valve seat must be machined with high precision in order to provide a leak-proof closure of the check valve. To prevent the steel balls from falling out of their cavity, a retainer is provided. This retainer is basically pot-shaped with a rim that is bent outwardly and partially covers the channel ports.
The housing of this check valve is designed as a cartridge that can be inserted into a valve block accommodating all valves of an anti-lock brake system, for instance. The housing includes a center cavity for insertion of an electro-magnetically operated valve which is by-passed by the channels having the check valves. With its pot-shaped portion, the retainer is press-fitted into a housing recess which is an extension of the center cavity. In order to open up a center channel for fluid coming from the center cavity, the retainer pot has a hole in its bottom.
This arrangement using a ball-type check valve generates undesired noise when the loose ball is hitting against the valve seat and the retainer.
It is therefore the object of the invention to provide a check valve that has a lower number of freely moving parts in order to reduce noise.
Another object of the invention is to design a valve that is easy to manufacture and therefore relatively cheap.
These objects are achieved with a check valve arrangement comprising a housing with a substantially flat surface area; at least one channel with an opening in the substantially flat surface area; a disc having a center hole and covering the channel opening; a retainer having a first portion extending through the center hole and fastened to the housing and having a second portion formed as a rim with a diameter larger than the center hole and a distance from the housing greater than the thickness of the disc; and a bias ring positioned between the rim and the disc and biasing the disc toward the housing.
A valve arrangement as proposed utilizes a disc for a valve member while eliminating the need for a ball. A valve seat in the common sense is unnecessary, too. Instead, a substantially flat surface interacts with the disc. In order to allow unidirectional flow only, the disc is biased toward the surface by means of an elastic bias ring which itself is held in place by a retainer extending through the center hole of the disc and thereby axially guiding the disc.
If desired, the flat surface can be supplemented with an embedded sealing ring to provide optimum sealing properties without precise machining of the surface.
By designing the disc and the retainer in rotational symmetry, a directional adjustment of the parts is made unnecessary.
The probably cheapest way of manufacturing a suitable retainer is to bend sheet metal into the desired shape.
If desired, this retainer can as well be provided with a center hole to open a passage for fluid as it has been realized in the prior-art example.
The invention will be described in further detail making reference to the attached drawings.